In Vivo Conjunctival Lymphatic Drainage Measured in Normal and Cancer Conditions by Photoacoustic Imaging

The conjunctiva is a mucous layer which provides a physical barrier against the external environment. Lymphatic vessels within the conjunctiva drain excess interstitial fluid, contribute to immune surveillance, and are involved ocular surface inflammatory and neoplastic diseases, including conjunctival melanoma. Our understanding of conjunctival lymphatics is limited due to the lack of in-vivo imaging techniques to quantify lymphatic drainage. Using photoacoustic imaging and a near-infrared tracer, we quantified lymphatic drainage from the conjunctiva to cervical lymph nodes in normal mice. Lymphatic drainage from the conjunctiva was also assessed in a model of pigmented conjunctival melanoma. Lymphatic drainage after tracer injection within or around the tumour was similar to that observed in normal mice. Additionally, we monitored patterns of tumour growth over time using photoacoustic quantification of the tumour melanin signal. This non-invasive quantitative platform may be useful for future studies of conjunctival lymphatics in conjunctival melanoma and other ocular diseases.M.Sc